Er-doped AlGaAs native oxides: photoluminescence characterization and process optimization

Abstract

We present 300 K photoluminescence (PL) characterization data for wet thermal native oxides of Al 0 58 Ga 0 42 As films grown by metal organic chemical vapor deposition and doped with Er via multiple high-energy ion implants (for 0.0675, 0.135, and 0.27 atomic percent (at.%) peak Er concentrations), and Al 0 5 Ga 0 5 As and Al 0 8 In 0 2 As films doped with Er (0.03-0.26 at.%) during molecular beam epitaxy crystal growth. Broad spectra with a 50-nm full-width at half-maximum and a PL peak at 1.534 m are observed, characteristic of Al 2 O 3 :Er films. The dependencies of PL intensity, spectra, and lifetime on annealing temperature (675 C-900 C), time (2-60 min) and As overpressure (0-0.82 atm) are studied to optimize the annealing process, with As considered as a possible quenching mechanism. Wet and dry-oxidized films are compared to explore the role of hydroxyl (OH) groups identified by Fourier transform infrared (FTIR) spectroscopy. FTIR experiments employing heavy water (D 2 O) suggest that OH groups in wet oxidized AlGaAs come mainly from post-oxidation adsorption of atmospheric moisture. AlGaAs:Er films wet oxidized with 0.1% O 2 added to the N 2 carrier gas show a fourfold PL intensity increase, doubled PL lifetime to 5.0 ms (0.27 at.% implanted sample), and the lowest degree of concentration quenching.

Low-loss nonselectively oxidized AlxGa1−xAs heterostructure waveguides

“…We have shown in studies reported elsewhere that AlGaAs native oxides are a viable host for optically active Er 3+ , supporting strong room temperature photoluminescence. [9][10][11] In our first demonstration of fully oxidized single-heterostructure ͑1.4 m Al 0.4 Ga 0.6 As/ 1.0 m Al 0.8 Ga 0.2 As͒ planar waveguides, an optical loss of ␣ = 2.5 cm −1 ͑10.9 dB/cm͒ was obtained at 0 = 1.55 m, while absorption of the external field by the substrate prevented characterization above the GaAs bandgap energy. 6 Conversion of a semiconductor heterostructure to an oxide heterostructure may also provide a means for realizing a mode expander.…”